Identification Of Maize Inbred Lines With Low-phosphorus Tolerance And Expression Pattern Of Long Non-coding RNA

Maize(Zea mays L.) is the largest acreage of grain crops, its yield and quality are directly related to national food security and people's living standards. The shortage of soil available phosphorus lead to the yield deduction by 40% and affect its quality. It has important theoretical and practical significance to research maize inbred line tolerance to low phosphorus. The resistant phosphorus and sensitive maize inbred lines were obtained by seedling and field screening. The mechanism of maize inbred lines under low phosphorus in morphological, physiological and molecular level were studied.the main results showed as follows:1. We studied 48 maize inbred lines tolerance to low phosphorus at seedling stage and found SPAD values (stress SPAD), plant height stress index and fresh weight of shoot under stress conditions had significant positive correlation with phosphorus deficiency tolerance. The maize inbred lines capacity of phosphorus deficiency tolerance was divided into five levels by membership function, the highly resistant inbred (tolerance to low phosphorus level 5) 4 lines:B73, Wu 9086, C0314 and Heinong34, resistant inbred (tolerance to low phosphorus level 4)9 lines, middle resistant inbred (tolerance to low phosphorus level 3) 28 lines, sensitive inbred (tolerance to low phosphorus level 2) 6 lines, highly sensitive inbred (tolerance to low phosphorus level 1)1 lines.2. Maize inbred lines with different capacity of phosphorus deficiency tolerance were selected and respose of low phosphorus to maize inbred lines was analyed. The yield of five maize inbred lines were decreased by 13.60%-68.66% under low phosphorus conditions, C531 (tolerance to low phosphorus level 2)> D340 (tolerance to low phosphorus level 3)> M731 (tolerance to low phosphorus level 3)> P138 (tolerance to low phosphorus level 4)> B73 (tolerance to low phosphorus level 5). It is consistent with evaluation of seedling tolerance to low phosphorus and it indicated that the stress SPAD, plant height stress index and shoot fresh weight under low phosphorus conditions could better evaluation of maize phosphorus deficiency tolerance.3. We studied maize tissue phosphorus content and photosynthetic parameters in seedling,jointing and tasseling stage. The field experiments show that the stress of low phosphorus can reduces the maize ground and underground phosphorus content, accumulation of phosphorus, phosphorus tolerance maize inbred underground phosphorus content decreased less amplitude. The stress of low phosphorus can make maize inbred lines net photosynthetic rate and stomatal conductance decreases, intercellular CO2 concentration increase, indicating that the photosynthetic rate of decline is caused by non-stomatal factors, phosphorus tolerance maize inbred lines changes to a lesser extent, explained that photosynthetic parameters is a important reference of maize tolerance to low phosphorus.4. Maize tissue phosphorus content and photosynthetic parameters at seedling, jointing and tasseling stages were measured. The field experiments showed that the maize ground and underground phosphorus content and the accumulation of phosphorus under low phosphorus conditions were decresed, phosphorus tolerance maize inbred underground phosphorus content decreased degree was amaller. The stress of low phosphorus can make maize inbred lines net photosynthetic rate and stomatal conductance decreases, intercellular CO2 concentration increase, indicating that the photosynthetic rate of decline is caused by non-stomatal factors, phosphorus tolerance maize inbred lines changes to a lesser extent, explained that photosynthetic parameters is a important reference of maize tolerance to low phosphorus.5. In order to research the mechanism of highly resistant inbred B73 and highly sensitive inbred C531 response to low phosphorus, the root acid phosphatase activity(APase) and tissue phosphorus content were measured under hydroponic conditions, the results show that maize total root length was reduced, total root length and root fresh weight of B73 were significantly higher than the C531, B73 root acid phosphatase activity(APase) is significantly higher than control, It is benificial to reuse organic phosphorus.6. The expression of Zmlnc088, Zmlnc077 and Zmlnc333 were induced by low phosphorus in the root of B73, The expression of Zmlnc088, Zmlnc077 and Zmlnc333 were not induced by low phosphorus in the root of C531, explaining that Zmlnc088, Zmlnc077 and Zmlnc333 in maize inbred line play an important role in resistance to low phosphorus.