The cotton MYB33 gene is a hub gene regulating the trade-off between plant growth and defense in Verticillium dahliae infection.

INTRODUCTION: Sessile plants engage in trade-offs between growth and defense capacity in response to fluctuating environmental cues. MYB is an important transcription factor that plays many important roles in controlling plant growth and defense. However, the mechanism behind how it keeps a balance between these two physiological processes is still largely unknown. OBJECTIVES: Our work focuses on the dissection of the molecular mechanism by which GhMYB33 regulates plant growth and defense. METHODS: The CRISPR/Cas9 technique was used to generate mutants for deciphering GhMYB33 functions. Yeast two-hybrid, luciferase complementary imaging, and co-immunoprecipitation assays were used to prove that proteins interact with each other. We used the electrophoretic mobility shift assay, yeast one-hybrid, and luciferase activity assays to analyze GhMYB33 acting as a promoter. A ß-glucuronidase fusion reporter and 5' RNA ligase mediated amplification of cDNA ends analysis showed that ghr-miR319c directedly cleaved the GhMYB33 mRNA. RESULTS: Overexpressing miR319c-resistant GhMYB33 (rGhMYB33) promoted plant growth, accompanied by a significant decline in resistance against Verticillium dahliae. Conversely, its knockout mutant, ghmyb33, demonstrated growth restriction and concomitant augmentation of V. dahliae resistance. GhMYB33 was found to couple with the DELLA protein GhGAI1 and bind to the specific cis-elements of GhSPL9 and GhDFR1 promoters, thereby modulating internode elongation and plant resistance in V. dahliae infection. The ghr-miR319c was discovered to target and suppress GhMYB33 expression. The overexpression of ghr-miR319c led to enhanced plant resistance and a simultaneous reduction in plant height. CONCLUSION: Our findings demonstrate that GhMYB33 encodes a hub protein and controls the expression of GhSPL9 and GhDFR1, implicating a pivotal role for the miR319c-MYB33 module to regulate the trade-offs between plant growth and defense.

Uptake of exogenous sugars and responses by rice root of young wild-type and ospk1 mutant seedlings / 生物工程学报

How root system responds to various environmental factors has not yet been fully elucidated. In root, the expression of OsPK1 is mainly in the maturation zone and the root-hair zone of root tip. It is unknown whether the uptake of exogenous sugars by rice seedlings is affected by downregulation of OsPK1. In this study, we used wild-type (WT) and ospk1 rice mutant plants to investigate the uptake of exogenous sugars and the responses of rice seedlings by adding sucrose to 1/2 MS medium or not. The contents of sucrose, glucose, fructose and galactose in leaf blades, sheathes and roots of rice seedlings were measured by GC-MS analysis. The result revealed that direct contact between root and exogenous sugars greatly elevates sugar levels of rice seedlings. And the root length of these seedlings is much longer than that of the seedlings grown in medium omitting exogenous sugars, suggesting that uptake of exogenous sugars by root promotes root elongation. Downregulation of OsPK1 has effects on sugar metabolism and the uptake of exogenous sugars. Semi-quantitative RT-PCR result showed that the expressions of OsPIP2;4, OsPIP2;5 and OsTIP2;1 (three aquaporin genes) in root were greatly upregulated by the direct contact between root and exogenous sugars.

Expression and functional analysis of OsRboh gene family in rice immune response / 生物工程学报

The preliminary role of respiratory burst oxidase homolog (Rboh) in plant immune response is defined, but the exact function of OsRboh gene in rice immune response and its expression pattern is yet unclear. In order to clarify the role of OsRboh in rice immune response, we screened seven OsRboh genes from the latest rice genome annotation database. The result of tissue specific expression analysis demonstrated that OsRbohD was expressed only in spike and calli, and OsRbohE and OsRbohF were only expressed in calli. The rest of OsRboh genes were constitutively expressed in rice. In addition, the expression level of OsRboh gene family was analyzed in the rice leaves respectively treated with salicylic acid (SA), methyl jasmonic acid (MeJA) and Xanthomonas oryzae PV. oryzae (Xoo) PXO99 strain by Real-time PCR, and H2O2 content was also quantified by spectrophotometry after the three treatments. The result shows that the expression of OsRbohA, B, C and D was increased under the treatments of SA, the expression of OsRbohA, B, C and G was increased under the treatments of MeJA, and the expression of OsRbohA and OsRbohB was induced by Xoo PXO99 strain. However, the levels of expression and responsive times of these genes were different. Moreover, all three treatments led to H2O2 accumulation. These OsRboh genes have functional roles in rice native immune response.

Overexpression of Spinacia oleracea betaine aldehyde dehydrogenase (SoBADH) gene confers the salt and cold tolerant in Gossypium hirsutum L / 生物工程学报

The open reading frame of Spinacia oleracea Betaine Aldehyde Dehydrogenase (SoBADH) was retrieved from Spinacia oleracea and inserted into the Agrobacterium tumefaciens binary vector pBin438, which was driven by CaMV35S promoter, and produced the new binary vector pBSB. A. tumefaciens LBA4404 carrying this plasmid was used in genetic transformation of plants. Forty-five primary transgenic plants were detected by PCR and verified by the Southern blotting from 65 regenerated plants, of which 27 transgenic plants had only one copy of T-DNA. The Northern blotting and Western blotting analysis indicated that the SoBADH gene had been transcribed mRNA and expression protein in the transgenic cotton lines. The testing of SoBADH activity of transgenic plant leaves showed that the enzyme activity was much higher than that of the non-transgenic cotton. The growth of transgenic plants was well under the salinity and freezing stress, whereas the non-transgenic plant grew poorly and even died. Challenging with salinity, the height and fresh weight of transgenic plants was higher compared with those of non-transgenic plants. Under the freezing stress, the relative conductivity of leaf electrolyte leakage of the transgenic cotton lines was lower than that of non-transgenic plants. These results demonstrated that the SoBADH gene could over express in the exogenous plants, and could be used in genetic engineering for cotton stress resistance.