Genes Affecting Cotton Fiber Length: A Systematic Review and Meta-Analysis

Cotton fiber length is an important measurement for application in the textile industry, and researchers are seeking to cultivate cotton plants with longer fibers. In this study, cotton fiber genes were systematically reviewed through meta-analysis in terms of extending and shortening fiber and the use of different research technologies for the first time. PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Baidu Xueshu databases were included as literature retrieval sources. A total of 21,467 articles were retrieved, and 45 articles were used in the final analysis. Data analysis was performed using RevMan 5.4 software. To shorten cotton fiber length, clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology was superior to virus-induced gene silencing (VIGS) technology and RNA interference (RNAi) technology [p = 0.002, MD = -1.05, 95% CI (-1.73, -0.37), Chi² = 39.89]. To increase cotton fiber length, CRISPR-Cas9 technology had a similar effect as VIGS technology [p = 0.12, MD = -0.59, 95% CI (-1.33, -0.15), Chi² = 0.17]. When some genes (GhLAC15, GhALDH7B4, GhMDHAR1A/GhDHAR2A, STTM-miR396b, GhMYB44, GhFP2, GhMYB7, GhKNL1, GhTCP4, GhHDA5, GhGalT1, GhKNOX6, GhXB38D, and GhBZR3) were damaged, cotton fiber length increased. Furthermore, we found that after gene interference, the fiber-shortening genes occurred more frequently than the fiber-elongating genes. Synergistic research on these genes may better promote cotton fiber elongation.