Molecular identification of variety purity in a cotton hybrid with unknown parentage using DNA-SSR markers.

Molecular identification of hybrid purity is difficult in regional trials of cotton varieties and hybrid trials. In particular, the molecular detection of hybrid purity has not yet been reported in the case of unknown parentage. In this study, we screened 5000 pairs of primers and chose 17 pairs of core simple sequence repeat (SSR) primers to determine the F1 purity of Han6402. The results showed that the purity based on SSR markers reached 100%. Twelve of the 17 pairs of primers exhibited co-dominant banding patterns, and 5 showed non-co-dominant banding patterns. Moreover, we constructed an F1 SSR fingerprinting profile that enabled the identification of the authenticity of Han 6402. Using these primers, we subsequently detected 44 individual F2 seedlings, and the results exhibited different extents of separation, in which the majority of genotypes were heterozygous with co-dominance at most of the loci that differed from each other. The results validated the underlying heterozygous status of the F2 population at the molecular level. Therefore, we conclude that the set of core SSR primers can be used for the laboratory identification of the authenticity and purity of cotton hybrids, not only for distinguishing Fl hybrids or segregating F2 populations, but also for detecting volunteer seeds as fake F1 hybrids in the cotton hybrid industry, based on the hybrid fingerprinting.

A putative miR172-targeted CeAPETALA2-like gene is involved in floral patterning regulation of the orchid Cymbidium ensifolium.

APETALA2 plays critical roles in establishing meristem and organ identity during plant floral development. In this study, we obtained a CeAP2-like gene by using the mRNA differential display technique to analyze the wild type and a multitepal mutant of the orchid Cymbidium ensifolium. The full-length cDNA encoding the CeAP2-like transcription factor shows significant similarity to the cDNA of AP2 from Erycina pusilla and contains nucleotides complementary to miR172. Using a transient gene expression system of Arabidopsis protoplasts, we found that the accumulation of CeAP2-like protein and transcripts was negatively regulated by miR172, indicating this gene as a putative target of miR172. Northern blotting revealed that CeAP2-like is dominantly expressed in the sepals and petals of the wild-type flower, and shows low expression in the gynostemium. In contrast, the accumulation of CeAP2-like transcripts decreased significantly, especially in the central part of the mutant flower, corresponding to its abnormal petals and the absence of the gynostemium. Furthermore, we found an antagonistic expression pattern between CeAP2-like and AGAMOUS in the wild type, representing A- and C-class genes that specify floral organ fate. However, this antagonistic distribution was modified in the multitepal mutant, and both genes showed lower expression than that in the wild type. This result suggested that the balance between CeAP2-like and AGAMOUS activity was important for the regulation of floral patterning in C. ensifolium. This study represents the first report on a class A gene and its regulatory role for floral development in the orchid C. ensifolium.

Ascorbate peroxidase from Jatropha curcas enhances salt tolerance in transgenic Arabidopsis.

Ascorbate peroxidase (APX) plays a central role in the ascorbate-glutathione cycle and is a key enzyme in cellular H2O2 me-tabolism. It includes a family of isoenzymes with different character-istics, which are identified in many higher plants. In the present study, we isolated the APX gene from Jatropha curcas L, which is similar with other previously characterized APXs as revealed by alignment and phylogenetic analysis of its deduced amino acid sequence. Real-time qPCR analysis showed that the expression level of JcAPX transcript significantly increased under NaCl stress. Subsequently, to elucidate the contribution of JcAPX to the protection against salt-induced oxi-dative stress, the expression construct p35S: JcAPX was created and transformed into Arabidopsis and transcribed. Under 150-mM NaCl stress, compared with wild type (WT), the overexpression of JcAPX in Arabidopsis increased the germination rate, the number of leaves, and the rosette area. In addition, the transgenic plants had longer roots, higher total chlorophyll content, higher total APX activity, and lower H2O2 content than the WT under NaCl stress conditions. These results suggested that higher APX activity in transgenic lines increases the salt tolerance by enhancing scavenging capacity for reactive oxygen spe-cies under NaCl stress conditions.