During anther development, the transformation of the microspore into mature pollen occurs under the protection of first the tetrad wall and later the pollen wall. Mutations in genes involved in this wall transition often lead to microspore rupture and male sterility; some such mutants, such as the reversible male sterile (rvms) mutant, are thermo/photoperiod-sensitive genic male sterile (P/TGMS) lines. Previous studies have shown that slow development is a general mechanism of P/TGMS fertility restoration. In this study, we identified restorer of rvms-2 (res2), which is an allele of QUARTET 3 (QRT3) encoding a polygalacturonase that shows delayed degradation of the tetrad pectin wall. We found that MS188, a tapetum-specific transcription factor essential for pollen wall formation, can activate QRT3 expression for pectin wall degradation, indicating a non-cell-autonomous pathway involved in the regulation of the cell wall transition. Further assays showed that a delay in degradation of the tetrad pectin wall is responsible for the fertility restoration of rvms and other P/TGMS lines, whereas early expression of QRT3 eliminates low temperature restoration of rvms-2 fertility. Taken together, these results suggest a likely cellular mechanism of fertility restoration in P/TGMS lines, that is, slow development during the cell wall transition of P/TGMS microspores may reduce the requirement for their wall protection and thus support their development into functional pollens, leading to restored fertility.

在花药发育过程中，小孢子向成熟花粉的转化首先是在四分体壁的保护下，然后是花粉壁的保护。与这种壁转变有关的基因突变通常会导致小孢子破裂和雄性不育。一些这样的突变体，例如可逆雄性不育 (rvms) 突变体，是热/光周期敏感的基因雄性不育 (P/TGMS) 系。以往研究表明，发育缓慢是P/TGMS生育力恢复的一般机制。在这项研究中，我们鉴定了 rvms-2 ( res2 ) 的恢复基因，它是QUARTET 3 (QRT3) 的等位基因，编码多聚半乳糖醛酸酶，显示四分体果胶壁的延迟降解。我们发现 MS188 是一种对花粉壁形成至关重要的绒毡层特异性转录因子，可以激活QRT3 表达以进行果胶壁降解，表明参与调节细胞壁转变的非细胞自主途径。进一步的分析表明，四分体果胶壁降解的延迟是rvms和其他 P/TGMS 系的生育力恢复的原因，而 QRT3 的早期表达消除了rvms-2的低温恢复 生育能力。总之，这些结果表明 P/TGMS 系中生育力恢复的一种可能的细胞机制，即 P/TGMS 小孢子在细胞壁转变过程中的缓慢发育可能会降低其壁保护的需求，从而支持它们发育成功能性花粉。 ，从而恢复生育能力。