Study on the cultivation of seedlings using buds of potato (Solanum tuberosum L.).

Background: Potato, a vegetable crop grown worldwide, has many uses, a short growth period, a large market demand and high economic benefits. The loss of potato seediness due to traditional potato growing methods is becoming increasingly evident, and research on new ways of growing potatoes is particularly important. Bud planting technology has the advantages of more reproduction, faster growth, and simplified maintenance of crop plants under cultivation. Methods: In this study, a bud planting method was adopted for the cultivation of potato seedlings. Specifically, we assessed different types of treatments for the production of high-quality buds and seedlings of potato. A total of four disease-free potato varieties (Fujin, Youjin, Zhongshu 4, and Feiwuruita) were selected, potato buds with three different lengths (3 cm, 5 cm, and 7 cm) were considered the T1, T2, and T3 treatments, and terminal buds, middle buds, and tail buds were used as the T4, T5, and T6 treatments. A nutrient pot experiment was performed following a randomized complete block design (RCBD) with three replicates and a natural control (CK) treatment. Cultivation was performed with the common horticultural practices of weeding and hoeing applied as needed. The photosynthetic indices, physiological indices, growth indices and quality of potato seedlings and quality of potato buds were measured at two-week intervals, and yield indices were measured when the final crop was harvested 14 weeks after planting. Results and Conclusions: Cultivation of seedlings from potato buds of different lengths increased the reproduction coefficient and reduced the number of seed potatoes needed for cultivation. All morphological, physiological, and yield indices showed positive trends. A potato bud length of 7 cm was optimal for raising seedlings. Moreover, buds located at the terminal of the potato yielded seedlings with the best quality. In conclusion, we recommend that our proven bud planting technique be adopted at the commercial level, which could support good crop production with maximum yield.

Genome design of hybrid potato.

Reinventing potato from a clonally propagated tetraploid into a seed-propagated diploid, hybrid potato, is an important innovation in agriculture. Due to deleterious mutations, it has remained a challenge to develop highly homozygous inbred lines, a prerequisite to breed hybrid potato. Here, we employed genome design to develop a generation of pure and fertile potato lines and thereby the uniform, vigorous F1s. The metrics we applied in genome design included the percentage of genome homozygosity and the number of deleterious mutations in the starting material, the number of segregation distortions in the S1 population, the haplotype information to infer the break of tight linkage between beneficial and deleterious alleles, and the genome complementarity of the parental lines. This study transforms potato breeding from a slow, non-accumulative mode into a fast-iterative one, thereby potentiating a broad spectrum of benefits to farmers and consumers.

Haplotype-resolved genome analyses of a heterozygous diploid potato.

Potato (Solanum tuberosum L.) is the most important tuber crop worldwide. Efforts are underway to transform the crop from a clonally propagated tetraploid into a seed-propagated, inbred-line-based hybrid, but this process requires a better understanding of potato genome. Here, we report the 1.67-Gb haplotype-resolved assembly of a diploid potato, RH89-039-16, using a combination of multiple sequencing strategies, including circular consensus sequencing. Comparison of the two haplotypes revealed ~2.1% intragenomic diversity, including 22,134 predicted deleterious mutations in 10,642 annotated genes. In 20,583 pairs of allelic genes, 16.6% and 30.8% exhibited differential expression and methylation between alleles, respectively. Deleterious mutations and differentially expressed alleles were dispersed throughout both haplotypes, complicating strategies to eradicate deleterious alleles or stack beneficial alleles via meiotic recombination. This study offers a holistic view of the genome organization of a clonally propagated diploid species and provides insights into technological evolution in resolving complex genomes.

The mutation of a PECTATE LYASE-LIKE gene is responsible for the Yellow Margin phenotype in potato.

KEY MESSAGE: The yellow margin (ym) gene was mapped to a 30-kb genomic region in potato and the mutation of a pectate lyase gene led to this phenotype. The practice of clonally propagating potato (Solanum tuberosum L.), which has been lasted for thousands of years, has caused the accumulation of deleterious alleles. Despite yellow margin (ym) being a common cause of a detrimental weak-vigor phenotype and reduced yield in diploid potato, the underlying gene has eluded discovery to date. In this paper, we mapped the ym gene to a 30-kb region containing four annotated genes. Among them, PGSC0003DMG402023481 encodes a pectate lyase-like gene (StPLL) with lower expression in ym plants than in the wild-type plants. PCR amplification confirmed a 4.1-kb deletion in the mutant allele of StPLL. Knockout of StPLL in diploid potato resulted in a similar phenotype with the ym plants. This study not only characterizes the ym allele but also provides the molecular tools to select and purge it from populations, while also deepening our understanding of the morphogenesis in potato.

The genetic basis of inbreeding depression in potato.

Inbreeding depression confers reduced fitness among the offspring of genetic relatives. As a clonally propagated crop, potato (Solanum tuberosum L.) suffers from severe inbreeding depression; however, the genetic basis of inbreeding depression in potato is largely unknown. To gain insight into inbreeding depression in potato, we evaluated the mutation burden in 151 diploid potatoes and obtained 344,831 predicted deleterious substitutions. The deleterious mutations in potato are enriched in the pericentromeric regions and are line specific. Using three F2 populations, we identified 15 genomic regions with severe segregation distortions due to selection at the gametic and zygotic stages. Most of the deleterious recessive alleles affecting survival and growth vigor were located in regions with high recombination rates. One of these deleterious alleles is derived from a rare mutation that disrupts a gene required for embryo development. This study provides the basis for genome design of potato inbred lines.

Generation of self-compatible diploid potato by knockout of S-RNase.

Re-domestication of potato into an inbred line-based diploid crop propagated by seed represents a promising alternative to traditional clonal propagation of tetraploid potato, but self-incompatibility has hindered the development of inbred lines. To address this problem, we created self-compatible diploid potatoes by knocking out the self-incompatibility gene S-RNase using the CRISPR-Cas9 system. This strategy opens new avenues for diploid potato breeding and will also be useful for studying other self-incompatible crops.

3 GHz, Yb-fiber laser-based, few-cycle ultrafast source at the Ti:sapphire laser wavelength.

We demonstrate a compact ultrafast source centered at 850 nm with >200 nm bandwidth (full width at half-maximum) based on a 3 GHz Yb-fiber master-oscillator-power-amplifier system. The output pulses (with up to 13 W average power) from the laser system are coupled into short (<50 mm) pieces of photonic crystal fibers to excite broadband fiber-optic Cherenkov radiation; the resulting broad phase-matching bandwidth due to short fiber length produces an upconverted spectrum spanning in the wavelength range of 750-950 nm with average power of 94, 184, and 380 mW for fiber length of 28, 37, and 48 mm, respectively. The spectrum generated from the 37 mm fiber is then dechirped by eight double-chirped mirrors, leading to compressed pulses ~14 fs in duration. Such an ultrafast source is a promising substitute of multigigahertz mode-locked Ti:sapphire lasers for applications in optical frequency metrology and multiphoton coherent microscopy.

Therapeutic efficacy of baclofen in refractory gastroesophageal reflux-induced chronic cough.

AIM: To evaluate the efficacy and safety of baclofen for treatment of refractory gastroesophageal reflux-induced chronic cough (GERC) unresponsive to standard anti-reflux therapy. METHODS: Sixteen patients with refractory GERC were given an 8-wk course of baclofen 20 mg three times a day as an add-on therapy to omeprazole. Changes in the cough symptom score, cough threshold to capsaicin, reflux symptom score and possible adverse effects were determined after treatment. The variables of multi-channel intraluminal impedance combined with pH monitoring were compared between responders and non-responders to baclofen. RESULTS: Twelve of 16 patients completed treatment. Cough disappeared or improved in 56.3% (9/16) of patients, including 6 patients with acid reflux-induced cough (66.7%) and 3 patients with non-acid reflux-induced cough (33.3%). With baclofen treatment, the cough symptom score began to decrease at week 2, was clearly decreased at week 6 and reached a minimum at week 8. At the end of therapy, the lowest concentration of capsaicin required for induction of ≥ 2 and ≥ 5 coughs increased from 0.98 (1.46) to 1.95 (6.82) µmol/L (Z = -2.281, P = 0.024) and from 1.95 (7.31) to 7.8 (13.65) µmol/L (Z = -2.433, P = 0.014), respectively, and the reflux symptom score decreased from 8.0 ± 1.6 to 6.8 ± 0.8 (t = 2.454, P = 0.023). The number of acid reflux episodes was significantly lower in responders than in non-responders. The main adverse effects were somnolence, dizziness and fatigue. CONCLUSION: Baclofen is a useful, but suboptimal treatment option for refractory GERC.

[Effect of radiofrequency of different temperatures and durations on motor conduction velocity of rat sciatic nerve].

OBJECTIVE: To evaluate the effect of radiofrequency of different temperatures and durations on sciatic nerve motor conduction velocity (MCV). METHODS: The bilateral sciatic nerve of 70 adult SD rats was dissected and exposed to radiofrequency ablation of different temperatures (30, 50, 55, 60, and 70 degrees C) and durations. The nerves were also exposed to increasing ablation temperatures from 30 degrees C to 50 degrees C with an increment of 5 degrees C (60 s at each temperature), and the changes in the MCV parameters were observed. RESULTS: The MCV parameters of rat sciatic nerve underwent significant changes following the radiofrequency exposures (P<0.05) except for the exposure at 55 degrees celsius; for 10 s. Below the temperature of 55 degrees celsius;, the MCV showed no obvious correlation to the exposure time for the group. For the nerves exposed to radiofrequency of 55 degrees celsius;, the latency was not correlated to the exposure time within 30 s, and data could be obtained from 55 s group; with these exceptions, the latency was found to positively while the negative phase wave inversely correlated to the exposure time. With fixed exposure time of 60 s, the MCV parameters were positively correlated to the ablation temperature (below 50 degrees C). Failure of MCV measurement occurred following exposures to 55 degrees celsius; for 50 s (or longer) or to 60 degrees C (or higher) for 10 s. CONCLUSION: Low-temperature radiofrequency (below 50 degrees C) produces definite effects on the MCV of rat sciatic nerve, and the effects are not associated with the exposure time, the mechanism of which remains unclear. At a given temperature, the ablation for sufficiently long durations can result in complete block of the MCV. At higher temperatures, radiofrequency exposure cause obvious nerve conduction block.