Resistance Of Arabidopsis EARLI1 Gene To Abiotic And Biotic Stresses

EARLIl (.early Arabidopsis aluminium-induced genel) belongs to HyPRP (hybrid proline rich protein) gene family. HyPRP makes up a subclass of PRP (proline rich protein) which is widely existed in higher plants. PRP represents one of five types of structural cell wall proteins that may function both in determination of specific structure of cell wall during plant development and in defense of plants against physical damage and pathogen infection. The aim of the present work is to understand the function of EARLIl gene under different stresses by investigating the expression patterns, physiological characters and morphological variations of EARLIl overexpression (OX) and T-DNA knock out (KO) lines.Homozygous OX lines were screened by kanamycin (Kan) selection. Higher expression level of EARLIl in these OX lines was confirmed by RT-PCR and Northern blot analysis. Homozygous T-DNA insertion lines were identified by PCR. Full length EARLIl mRNA could not be detected by RT-PCR, while only a shorter transcript band could be detected by Northern blot analysis in KO lines.Early-flowering Arabidopsis ecotype Columbia-0 (Col-0) was used to analyse the expression of EARLIl under various stresses. RT-PCR and Northern blot analysis revealed that EARLIl could be induced by NaCl. Morphological observation and physiological analysis showed that OX lines of EARLIl had stronger salt and drought tolerance compared with Col-0 wild type plants, while the tolerance of EARLIl KO lines was decreased obviously.Northern blot analysis showed that EARLIl could also be induced by inoculation of Botrytis cinerea Pers.ex of galic sprouts. Germination of Botrytis cinerea spores deposited on leaf surface of wild type, overexpression and T-DNA knock out plants were monitored microscopically after trypan blue staining. Hyphae of Botrytis cinerea grew vigorously on leaf surface of EARLIl KO lines, while their growth was inhibited on leaf surface of OX lines. Yeast cells harboring EARLIl had a statistically significant (P<0.05) decrease in survival rates in comparison with yeast cells transformed with empty vector. Morphological and scanning electron microscopic observation showed that KO plants were attacked earlier and more frequently than the Col-0 wild type plants by insects.In order to further confirm the function of EARLIl gene, it was introduced into Nicotiana tobacum (Qin Yan 95) by Agrobacterium tumefaciens-mediated transformation. After Kan selection, the putative transgenic plants were verified by PCR, RT-PCR and Northern blot analysis, and salt tolerance of EARLIl was also supported by transgenic tobacco.