Studies On Screening Of Phosphorus Efficient Arabidopsis Mutants And Its Nutritional Mechanism

Genotype differences of phosphorus efficiency among 5143 Arabidopsis mutants were investigated under soil culture. Two treatments, P-deficiency (CK) and P-sufficiency (+P), were made. The phosphorus efficiency of different mutants was estimated with the coefficient of (-P/+P). The nutritional mechanism was primarily studied. The main results were found out as follows:First, different P concentration was conducted to plant Arabidopsis. Plants appeared P-deficient symptom and the difference between different ecotypes was marked when the concentration of P was 10 mg/L, 10 mg/L was confirmed as the concentration of the treatment of P-deficiency. When the concentration of P was 100 mg/L, plants grew very well, 100 mg/L was confirmed as the concentration of the treatment of P-sufficiency.Second, four experiments were conducted between October, 2002 and February, 2004. Fourteen phosphorus efficient mutants and twenty-one phosphorus inefficient mutants were found in the primary screening. And through the further validation in the forth experiment, two phosphorus efficient mutants of CS31018, CS19973 and one phosphorus inefficient mutant of CS4579 were confirmed.Third, under nutrient solution culture, further validation experiment was conducted, the result was identical with the screening experiment under soil culture, phosphorus efficient mutants of CS31018, CS19973 could endure phosphorus deficient menace under P-deficient condition, and have high potential production under P-sufficient condition, phosphorus inefficient mutant of CS4579 could neither endure phosphorus deficient menace nor obtain high yield.Forth, phosphorus efficient mutants of CS31018, CS19973 and phosphorus inefficient mutant of CS4579 as well as the wild Col were planted under nutritional solution culture, and the nutritional mechanism was primarily studied. Results indicated that under P-deficient condition efficient mutants of CS31018, CS19973 can build more weight of dry matter and P accumulation, in terms of this, inefficient mutant of CS4579 was weaker, which indicated that efficient mutants were realized high efficient because they could utilize phosphorus availability. As for P accumulation, efficient mutants were much higher than inefficient mutant, which indicated that efficient mutants had higher absorbing and using phosphorus ability compared with inefficient mutant. As far as phosphorus transport coefficient (PTC) was concered, under P-deficient condition,phosphorus efficient mutants of CS310^ CS19973 was lower than phosphorus inefficient mutant of CS4579, which indicated that P-deficient had lower effect on the distribute phosphorus ability from roots to shoots of efficient mutants than on that of inefficient mutant. Thus it can be seen, the efficient mechanism was that efficient mutants had higher absorbing , utilizing and transporting phosphorus ability.Fifth, under nutrient solution culture, Acid Phosphatase (Apase) was researched, with the decreasing supplied phosphorus level the difference of Apase mainly embodied on the changing degree of Apase acticity, compared with P-sufficient, the Apase activity of efficient mutants increased more than inefficient mutant under P-deficient. efficient mutants could excrete more Apase to adapt phosphorus deficient menace, and increasing the utility phosphorus efficiency to maintain well-balanced growth.