datasource vs. persistence.xml for database config parameter - spring

Question

In my project I'm using spring with jpa, and when I arrive to the config files, I mean appContext.xml and persistence.xml, I have encoutered the following situation : when I put the db config in the persistence.xml and I remove the datasource from the appContext.xml nothing works but when I move the bd config to the appContext into the dataSource tag (with properties) the app is running, can anyone explain this? thanks in advance!
Persistence.xml :
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="test" transaction-type="RESOURCE_LOCAL">
<class>ma.persistence.dto.Subscriber</class>
<class>ma.persistence.dto.Profile</class>
<class>ma.dto.Title</class>
</persistence-unit>
</persistence>
AppContext.xml :
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:component-scan base-package="ma.persistence"/>
<context:annotation-config />
<tx:annotation-driven />
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource"
p:driverClassName="com.mysql.jdbc.Driver" p:url="jdbc:mysql://localhost:3306/MyDB"
p:username="username" p:password="password" />
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
p:dataSource-ref="dataSource" p:jpaVendorAdapter-ref="jpaAdapter">
<property name="loadTimeWeaver">
<bean
class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />
</property>
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="databasePlatform"
value="org.hibernate.dialect.MySQLInnoDBDialect" />
</bean>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
p:entityManagerFactory-ref="entityManagerFactory" />
<bean id="jpaAdapter"
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
p:database="MYSQL" p:showSql="true" />