AUTHOR=Wei Wei , Ju Jisheng , Zhang Xueli , Ling Pingjie , Luo Jin , Li Ying , Xu Wenjuan , Su Junji , Zhang Xianliang , Wang Caixiang 

TITLE=GhBRX.1, GhBRX.2, and GhBRX4.3 improve resistance to salt and cold stress in upland cotton

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1353365

DOI=10.3389/fpls.2024.1353365

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Abiotic stress during growth readily reduces cotton crop yield. The different survival tactics of plants include the activation of numerous stress response genes, such as <italic>BREVIS RADIX</italic> (<italic>BRX</italic>).</p></sec><sec><title>Methods</title><p>In this study, the <italic>BRX</italic> gene family of upland cotton was identified and analyzed by bioinformatics method, three salt-tolerant and cold-resistant <italic>GhBRX</italic> genes were screened. The expression of <italic>GhBRX.1</italic>, <italic>GhBRX.2</italic> and <italic>GhBRXL4.3</italic> in upland cotton was silenced by virus-induced gene silencing (VIGS) technique. The physiological and biochemical indexes of plants and the expression of related stress-response genes were detected before and after gene silencing. The effects of <italic>GhBRX.1</italic>, <italic>GhBRX.2</italic> and <italic>GhBRXL4.3</italic> on salt and cold resistance of upland cotton were further verified.</p></sec><sec><title>Results and discussion</title><p>We discovered 12, 6, and 6 <italic>BRX</italic> genes in <italic>Gossypium hirsutum</italic>, <italic>Gossypium raimondii</italic> and <italic>Gossypium arboreum</italic>, respectively. Chromosomal localization indicated that the retention and loss of <italic>GhBRX</italic> genes on homologous chromosomes did not have a clear preference for the subgenomes. Collinearity analysis suggested that segmental duplications were the main force for <italic>BRX</italic> gene amplification. The upland cotton genes <italic>GhBRX.1</italic>, <italic>GhBRX.2</italic> and <italic>GhBRXL4.3</italic> are highly expressed in roots, and <italic>GhBRXL4.3</italic> is also strongly expressed in the pistil. Transcriptome data and qRT‒PCR validation showed that abiotic stress strongly induced <italic>GhBRX.1</italic>, <italic>GhBRX.2</italic> and <italic>GhBRXL4.3</italic>. Under salt stress and low-temperature stress conditions, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and the content of soluble sugar and chlorophyll decreased in <italic>GhBRX.1-</italic>, <italic>GhBRX.2-</italic> and <italic>GhBRXL4.3</italic>-silenced cotton plants compared with those in the control (TRV: 00). Moreover, <italic>GhBRX.1</italic>-, <italic>GhBRX.2</italic>- and <italic>GhBRXL4.3</italic>-silenced cotton plants exhibited greater malondialdehyde (MDA) levels than did the control plants. Moreover, the expression of stress marker genes (<italic>GhSOS1</italic>, <italic>GhSOS2</italic>, <italic>GhNHX1</italic>, <italic>GhCIPK6</italic>, <italic>GhBIN2</italic>, <italic>GhSnRK2.6</italic>, <italic>GhHDT4D</italic>, <italic>GhCBF1</italic> and <italic>GhPP2C</italic>) decreased significantly in the three target genes of silenced plants following exposure to stress. These results imply that the <italic>GhBRX.1</italic>, <italic>GhBRX.2</italic> and <italic>GhBRXL4.3</italic> genes may be regulators of salt stress and low-temperature stress responses in upland cotton.</p></sec>