NaPi/SX-RNase segregates as a functional S-RNase and is induced under phosphate deficiency in Nicotiana alata

HERNÁN ROJAS; CAROLINA CASPANI; ESCOBAR, ELIANA GISELLE; RODRIGO QUIROGA

BIOLOGIA PLANTARUM

SPRINGER

Lugar: Berlin; Año: 2018 vol. 62 p. 261 - 268

0006-3134

In plants, class III T2 RNases involve two groups ofstructurally similar proteins, but with different biological functions:S-RNases and non-S-RNases. S-RNases have been involved in self-incompatibilitywhile non-S-RNases have been implicated in stress responses. Here we report anovel class III RNase gene termed NaPi/Sx-RNase,which works both in self-incompatibility and in response to phosphatedeficiency. The NaPi/Sx-RNasewas identified  in roots of Nicotiana alata grown in the absence ofinorganic phosphate. Phylogenetic analysis showed that NaPi/Sx-RNase was included within the class III RNase T2group. The NaPi/Sx-RNasewas expressed in styles and its temporal expression increased in parallel tostylar development, with a slight decrease after anthesis. Progeny analysisshowed that NaPi/Sx-RNase andS107-RNase, a functionalallele of the self-incompatibility system, segregated in a 1:1 ratio. Theprogeny segregation of a semicompatible cross, in which NaPi/Sx-RNase was shared by the two parents, exhibited apattern consistent with a functional S-RNaseallele. Considering genetic segregation, primary structure, and physiologicalrole, the NaPi/Sx-RNase may be either an S-RNase with diversifiedfunctions or a non-S-RNase linked to the S-locus.To our knowledge, this is the first evidence for a specific function of the S-locus other than theself-incompatibility reaction. These results support the hypothesis that theself-incompatibility and stress responses may have evolved from a commonorigin.